Elevated Temperature Mechanical Properties of Devitrified Metallic Glass

2004 ◽  
Vol 821 ◽  
Author(s):  
Nathan A. Mara ◽  
Alla V. Sergueeva ◽  
A.K. Mukherjee
Keyword(s):  
Elevated Temperature ◽  
Metallic Glass ◽  
Grain Growth ◽  
Single Phase ◽  
Tensile Tests ◽  
Grain Boundary Sliding ◽  
Brittle Behavior ◽  
Materials Research ◽  
Boundary Sliding ◽  
Research Grant

AbstractElevated temperature tensile tests of different microstructures arising from different heat treatments of the Fe-based metallic glass Vitroperm (Fe73.5Cu1Nb3Si15.5B7) are presented. An anneal at 600°C for 1h yields a single phase μ-Fe microstructure with equiaxed, randomly oriented 15 nm grains, which is an ideal candidate for study of material properties at diminishing length scale. This microstructure has good stability during tensile testing at 600°C, showing a strain rate exponent correlating to grain boundary sliding (m=0.5), but little ductility, and strengths to 1250 MPa. The brittle behavior could be attributed to the lack of dislocation activity at such length scales. At temperatures up to 725°C, grain growth occurs, leading to elongations as large as 65% at flow stresses of 250 MPa. Precipitation of a second Nb-rich phase accompanies the grain growth. This investigation is supported by NSF, Division of Materials Research, grant NSF-DMR-0240144.

Recrystallization and Grain Growth in Rocks and Minerals

2004 ◽  
Vol 467-470 ◽  
pp. 545-550 ◽  
Author(s):  
David J. Prior ◽  
Michel Bestmann ◽  
Angela Halfpenny ◽  
Elisabetta Mariani ◽  
Sandra Piazolo ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Grain Growth ◽  
Grain Boundary Sliding ◽  
Data Sets ◽  
Nucleation Process ◽  
Ebsd Data ◽  
Boundary Sliding ◽  
And Migration

Misorientation analysis, using EBSD data sets, has enabled us to constrain better recrystallization mechanisms in rocks and minerals. Observed microstructures are not explicable in terms of recovery, boundary bulging and migration alone. We have to invoke either a nucleation process (physics unknown) or grain rotations that are not related to grain or boundary crystallography. Such rotations can occur by diffusion accommodated grain boundary sliding and this mechanism explains best the microstructure and texture of recrystallized grains in some rocks.

Tribological Behavior of Mg-Mg2Si In Situ Composite

2012 ◽  
Vol 710 ◽  
pp. 401-406
Author(s):  
Kumaraswamy Kaliamma Ajith Kumar ◽  
Uma Thanu Subramonia Pillai ◽  
Bellambettu Chandrasekhara Pai ◽  
Madhusudan Chakraborty
Keyword(s):  
Elevated Temperature ◽  
Wear Rate ◽  
Grain Boundary ◽  
Tribological Behavior ◽  
Grain Boundary Sliding ◽  
Dry Sliding ◽  
Boundary Sliding ◽  
Si Content ◽  
State Processing

Mg-Mg2Si in-situ composites by the addition of Si in Mg have become more attractive since the Mg2Si phase impedes the grain boundary sliding at elevated temperature because of its inherent properties which greatly improve the heat and wear resistances. In the present work, Mg-Mg2Si composites have been prepared by the liquid state processing with different amount of silicon additions. The microstructure and dry sliding tribological behavior of the composites have been studied. SEM studies reveal the wear mechanisms involved in these composites. The results indicate that wear rate of the composites is a function of Mg2Si content in the composite. The effect of Mg2Si morphology and distribution on the overall mechanism is also discussed.

Enhanced Tensile Ductility of AZ80 Magnesium Alloy

2011 ◽  
Vol 284-286 ◽  
pp. 1635-1638
Author(s):  
Jun Qiao ◽  
Yu Wang ◽  
Guo Dong Shi ◽  
Bao Xin Nie
Keyword(s):  
Tensile Tests ◽  
Grain Boundary Sliding ◽  
Dislocation Creep ◽  
Strain Rates ◽  
Premature Failure ◽  
Az80 Magnesium Alloy ◽  
Coarse Grains ◽  
Elongation To Failure ◽  
Boundary Sliding ◽  
Cavity Evolution

Tensile behaviors of extruded and rolled AZ80 Mg alloy were investigated with elongation-to-failure tensile tests at constant temperatures of 300 °C, 350 °C, 400 °C, and 450 °C, and constant strain rates of 10-2s-1and 10-3s-1. Experimental data show that the material exhibits tensile ductilities of over 100% at 400 °C and 450 °C, featured by long steady state deformation. Microstructure studies show that annealed coarse grains were remained in the gauge region during the tensile tests, and the enhanced tensile ductilities resulted from dislocation creep, other than dynamic recrystallization or grain boundary sliding. Cavity evolution and recrystallized coarse grains near fracture end caused premature failure of the material.

scholarly journals On the Controversy about the Presence of Grain Boundary Sliding in Mg AZ31

2012 ◽  
Vol 735 ◽  
pp. 22-25
Author(s):  
Carl Boehlert ◽  
Zhe Chen ◽  
Iván Gutierrez-Urrutia ◽  
Javier Llorca ◽  
María Teresa Pérez-Prado
Keyword(s):  
Grain Boundary ◽  
Sheet Material ◽  
Plastic Anisotropy ◽  
Tensile Tests ◽  
Grain Boundary Sliding ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Significant Drop ◽  
Az31 Sheet ◽  
Boundary Sliding

Highly-textured, rolled AZ31 sheet material shows a significant drop in the plastic anisotropy (r-value; r=ew/et) in tension between 25°C and 200°C. This behavior was initially explained as a result of the increased activity of non-basal slip with increased temperature. Other authors suggested, however, that the mechanism responsible for this phenomenon was the activation of grain boundary sliding (GBS). Here, in-situ tensile tests have been carried out in an SEM at various temperatures in order to obtain further evidence of the role of GBS during moderate to high temperature deformation of Mg alloys, which remains highly controversial.

scholarly journals Characterization of Intergranular Phases in Tetragonal and Cubic Yttria-Stabilized Zirconia

1998 ◽  
Vol 4 (S2) ◽  
pp. 584-585
Author(s):  
N.D. Evans ◽  
P.H. Imamura ◽  
J. Bentley ◽  
M.L. Mecartney
Keyword(s):  
Grain Growth ◽  
Hot Isostatic Pressing ◽  
Tetragonal Zirconia ◽  
Potential Method ◽  
Grain Boundary Sliding ◽  
Fine Grained ◽  
Net Shape Forming ◽  
Boundary Sliding ◽  
Ceramic Manufacturing

Achieving superplasticity in fine-grained ceramics is a potential method to lower energy costs associated with ceramic manufacturing via net shape forming. Superplasticity is intrinsic in 3-mol%- yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP), and can be enhanced by addition of glass to form intergranular phases which are thought to both limit grain growth and promote grain boundary sliding during processing (sintering and hot isostatic pressing). This permits processing at lower temperatures. However, superplasticity has not been observed in 8-mol%-yttria-stabilized cubic zirconia (8Y-CSZ), ostensibly due to its larger grain size and high grain growth rates.3,4 As part of a larger study, high-spatial-resolution energy-dispersive X-ray spectrometry (EDS) has been performed on 3Y-TZP and 8Y-CSZ specimens doped with various glassy phases to characterize intergranular compositions.Zirconia powders were mixed with glass to produce specimens having either 1 wt % lithiumaluminum- silicate, 1 wt % barium-silicate, or 1 wt % borosilicate. Some specimens were prepared without added glass.

scholarly journals Highly Enhanced Hot Ductility Performance of Advanced SA508-4N RPV Steel by Trace Impurity Phosphorus and Rare Earth Cerium

Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1598
Author(s):  
Yu Guo ◽  
Yu Zhao ◽  
Shenhua Song
Keyword(s):  
Single Phase ◽  
Boundary Segregation ◽  
Tensile Tests ◽  
Phase Region ◽  
Hot Ductility ◽  
Hot Workability ◽  
Rpv Steel ◽  
Ductility Trough ◽  
Boundary Sliding ◽  
Reduction Of Area

Advanced SA508-4N RPV steel samples, unadded, P-added, and P+Ce-added, are investigated on their hot ductility behavior. Hot tensile tests are carried out in the temperature range of 750 to 1000 °C through a Gleeble 1500D machine. It is demonstrated that the deformation temperatures of all the three steels are located in the austenite single-phase region. There is no ductility trough present for the P+Ce-added steel, but the unadded one exhibits a deep ductility trough. The reduction of area (RA) of the former is always higher than 75% and increases with rising temperature until reaching ~95% at 900 °C or above, whereas the lowest RA value of the latter is only ~50% at 850 °C. Microanalysis indicates that the grain boundary segregation of P and Ce takes place in the tested P+Ce-added steel. This may restrain the boundary sliding so as to improve the hot ductility behavior of the steel. Furthermore, the addition of P and Ce is able to facilitate the occurrence of the dynamic recrystallization (DR) of the steel, lowering the initial temperature of DR from ~900 to ~850 °C and thereby enhancing the hot ductility performance. Consequently, the combined addition of P and Ce can significantly improve the hot ductility of SA508-4N RPV steel, thereby improving its continuous casting performance and hot workability.

Mechanisms-based constitutive equations for the superplastic behaviour of a titanium alloy

1996 ◽  
Vol 31 (3) ◽  
pp. 187-196 ◽  
Author(s):  
M Zhou ◽  
F P E Dunne
Keyword(s):  
Titanium Alloy ◽  
Grain Boundary ◽  
Grain Growth ◽  
Constitutive Equations ◽  
Grain Boundary Sliding ◽  
Deformation Mechanisms ◽  
Diffusional Creep ◽  
Dislocation Creep ◽  
Boundary Sliding

Mechanisms-based constitutive equations are proposed for the high-temperature behaviour of a class of titanium alloys, for which the deformation mechanisms include diffusional creep, grain boundary sliding, dislocation creep and grain growth. A computational procedure has been developed for the determination of the constitutive equations from a material database. The constitutive equations and the procedure for their determination have been validated by modelling the behaviour of the titanium alloy Ti-6Al-4V at 927°C. It is shown that the procedure developed for the determination of the mechanisms-based constitutive equations can be used to identify the important deformation mechanisms in operation for particular stress, temperature and strain rate conditions. For the case of the Ti-6Al-4V material, the procedure developed correctly predicts the material hardening due to grain growth and indicates that an additional hardening mechanism operates. In addition, the procedure is able to identify grain boundary sliding as a predominant deformation mechanism. The constitutive equations, which are generic in nature, and the procedure for their determination are applicable over a range of materials and are suitable for modelling the macroscopic and the important microscopic aspects of material behaviour during processing. The equations may be readily determined using the procedure presented, which is highly suitable for development as an expert system, to completely automate the process.

Tensile Properties of Hot Extruded Mg-Zn-Nd-Y-Zr Alloy at Elevated Temperatures

2011 ◽  
Vol 415-417 ◽  
pp. 1157-1163
Author(s):  
Xiao Zhou ◽  
Hai Tao Zhou ◽  
Zhen Dong Zhang ◽  
Rui Rui Liu ◽  
Li Bin Liu
Keyword(s):  
Strain Rate ◽  
Elevated Temperatures ◽  
Peak Stress ◽  
Tensile Tests ◽  
Grain Boundary Sliding ◽  
Strain Rates ◽  
Zk60 Alloy ◽  
Boundary Sliding ◽  
Increasing Temperature ◽  
Zr Alloy

Mechanical properties of extruded Mg-Zn-Nd-Y-Zr alloy are investigated by tensile tests at various temperatures range from room temperature to 350°C with strain rates of 6.0×10-4-6.0×10-1s-1. It is found that the peak decrease with increasing temperature and decreasing strain rate, while the elongation increases with increasing temperature and decreasing strain rate. When deformation temperature is over 250°C, superplasticity occurs. This is ascribed to grain boundary sliding accommodated cavities growth. . At low temperature, the peak stress are a relatively higher than that of ZK60 alloy. This is explained by the grain refining effect and the precipitates of Mg9Nd and Mg6Zn3Y2.

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